Premium
Thermal stability and conformational transitions of scrapie amyloid (prion) protein correlate with infectivity
Author(s) -
Safar Jiri,
Roller Peter P.,
Gajdusek D. Carleton,
Gibbs Clarence J.
Publication year - 1993
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560021220
Subject(s) - scrapie , infectivity , prion protein , prion proteins , amyloid (mycology) , protein folding , chemistry , biophysics , virology , protein stability , amyloid β , biology , biochemistry , virus , medicine , pathology , disease , inorganic chemistry
Abstract The scrapie amyloid (prion) protein (PrP27–30) is the protease‐resistant core of a larger precursor (PrP Sc ) and a component of the infectious scrapie agent; the potential to form amyloid is a result of a posttranslational event or conformational abnormality. The conformation, heat stability, and solvent‐induced conformational transitions of PrP27–30 were studied in the solid state in films by CD spectroscopy and correlated with the infectivity of rehydrated and equilibrated films. The exposure of PrP27–30 in films to 60 °C, 100 °C, and 132 °C for 30 min did not change the β ‐sheet secondary structure; the infectivity slightly diminished at 132 °C and correlated with a decreased solubility of PrP27–30 in sodium dodecyl sulfate (SDS), probably due to cross‐linking. Exposing PrP27–30 films to formic acid (FA), trifluoroacetic acid (TFA), trifluoroethanol (TFE), hexafluoro‐2‐propanol (HFIP), and SDS transformed the amide CD band, diminished the mean residue ellipticity of aromatic bands, and inactivated scrapie infectivity. The convex constraint algorithm (CAA) deconvolution of the CD spectra of the solvent‐exposed and rehydrated solid state PrP27–30 identified five common spectral components. The loss of infectivity quantitatively correlated with a decreasing proportion of native, β ‐pleated sheet‐like secondary structure component, an increasing amount of α ‐helical component, and an increasingly disordered tertiary structure. The results demonstrate the unusual thermal stability of the β ‐sheet secondary structure of PrP27–30 protein in the solid state. The conformational perturbations of PrP27–30 parallel the changes in infectivity and suggest that the β ‐sheet structure plays a key role in the physical stability of scrapie amyloid and in the ability to propagate and replicate scrapie.